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  • Dynamic obfuscation by self-modifying code

    - by Fallout2
    Hi all, Here what's i am trying to do: assume you have two fonction void f1(int *v) { *v = 55; } void f2(int *v) { *v = 44; } char *template; template = allocExecutablePages(...); char *allocExecutablePages (int pages) { template = (char *) valloc (getpagesize () * pages); if (mprotect (template, getpagesize (), PROT_READ|PROT_EXEC|PROT_WRITE) == -1) { perror (“mprotect”); } } I would like to do a comparison between f1 and f2 (so tell what is identical and what is not) (so get the assembly lines of those function and make a line by line comparison) And then put those line in my template. Is there a way in C to do that? THanks Update Thank's for all you answers guys but maybe i haven't explained my need correctly. basically I'm trying to write a little obfuscation method. The idea consists in letting two or more functions share the same location in memory. A region of memory (which we will call a template) is set up containing some of the machine code bytes from the functions, more specifically, the ones they all have in common. Before a particular function is executed, an edit script is used to patch the template with the necessary machine code bytes to create a complete version of that function. When another function assigned to the same template is about to be executed, the process repeats, this time with a different edit script. To illustrate this, suppose you want to obfuscate a program that contains two functions f1 and f2. The first one (f1) has the following machine code bytes Address Machine code 0 10 1 5 2 6 3 20 and the second one (f2) has Address Machine code 0 10 1 9 2 3 3 20 At obfuscation time, one will replace f1 and f2 by the template Address Machine code 0 10 1 ? 2 ? 3 20 and by the two edit scripts e1 = {1 becomes 5, 2 becomes 6} and e2 = {1 becomes 9, 2 becomes 3}. #include <stdlib.h> #include <string.h> typedef unsigned int uint32; typedef char * addr_t; typedef struct { uint32 offset; char value; } EDIT; EDIT script1[200], script2[200]; char *template; int template_len, script_len = 0; typedef void(*FUN)(int *); int val, state = 0; void f1_stub () { if (state != 1) { patch (script1, script_len, template); state = 1; } ((FUN)template)(&val); } void f2_stub () { if (state != 2) { patch (script2, script_len, template); state = 2; } ((FUN)template)(&val); } int new_main (int argc, char **argv) { f1_stub (); f2_stub (); return 0; } void f1 (int *v) { *v = 99; } void f2 (int *v) { *v = 42; } int main (int argc, char **argv) { int f1SIZE, f2SIZE; /* makeCodeWritable (...); */ /* template = allocExecutablePages(...); */ /* Computed at obfuscation time */ diff ((addr_t)f1, f1SIZE, (addr_t)f2, f2SIZE, script1, script2, &script_len, template, &template_len); /* We hide the proper code */ memset (f1, 0, f1SIZE); memset (f2, 0, f2SIZE); return new_main (argc, argv); } So i need now to write the diff function. that will take the addresses of my two function and that will generate a template with the associated script. So that is why i would like to compare bytes by bytes my two function Sorry for my first post who was not very understandable! Thank you

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  • Refactoring Singleton Overuse

    - by drharris
    Today I had an epiphany, and it was that I was doing everything wrong. Some history: I inherited a C# application, which was really just a collection of static methods, a completely procedural mess of C# code. I refactored this the best I knew at the time, bringing in lots of post-college OOP knowledge. To make a long story short, many of the entities in code have turned out to be Singletons. Today I realized I needed 3 new classes, which would each follow the same Singleton pattern to match the rest of the software. If I keep tumbling down this slippery slope, eventually every class in my application will be Singleton, which will really be no logically different from the original group of static methods. I need help on rethinking this. I know about Dependency Injection, and that would generally be the strategy to use in breaking the Singleton curse. However, I have a few specific questions related to this refactoring, and all about best practices for doing so. How acceptable is the use of static variables to encapsulate configuration information? I have a brain block on using static, and I think it is due to an early OO class in college where the professor said static was bad. But, should I have to reconfigure the class every time I access it? When accessing hardware, is it ok to leave a static pointer to the addresses and variables needed, or should I continually perform Open() and Close() operations? Right now I have a single method acting as the controller. Specifically, I continually poll several external instruments (via hardware drivers) for data. Should this type of controller be the way to go, or should I spawn separate threads for each instrument at the program's startup? If the latter, how do I make this object oriented? Should I create classes called InstrumentAListener and InstrumentBListener? Or is there some standard way to approach this? Is there a better way to do global configuration? Right now I simply have Configuration.Instance.Foo sprinkled liberally throughout the code. Almost every class uses it, so perhaps keeping it as a Singleton makes sense. Any thoughts? A lot of my classes are things like SerialPortWriter or DataFileWriter, which must sit around waiting for this data to stream in. Since they are active the entire time, how should I arrange these in order to listen for the events generated when data comes in? Any other resources, books, or comments about how to get away from Singletons and other pattern overuse would be helpful.

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  • Rails architecture questions

    - by justinbach
    I'm building a Rails site that, among other things, allows users to build their own recipe repository. Recipes are entered either manually or via a link to another site (think epicurious, cooks.com, etc). I'm writing scripts that will scrape a recipe from these sites given a link from a user, and so far (legal issues notwithstanding) that part isn't giving me any trouble. However, I'm not sure where to put the code that I'm writing for these scraper scripts. My first thought was to put it in the recipes model, but it seems a bit too involved to go there; would a library or a helper be more appropriate? Also, as I mentioned, I'm building several different scrapers for different food websites. It seems to me that the elegant way to do this would be to define an interface (or abstract base class) that determines a set of methods for constructing a recipe object given a link, but I'm not sure what the best approach would be here, either. How might I build out these OO relationships, and where should the code go?

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  • Using Remote Web Server to Initialize iPhone App

    - by Chris_K
    My iPhone app relies on a vendor's XML feed to provide data. But that feed is not locked down. The vendor could change the format of the XML at any time, although so far they've promised not to. Since I might want to tell my app to use a different URL for its data source, I'd like to set up a single "Command Central" Web page, on my own server, to direct the app to the correct data source. In other words, each time my app starts, in the background and unseen by the user, it would visit "http://www.myserver.com/iphoneapp_data_sources.xml" to retrieve the URL for retrieving data from my vendor. That way, if my vendor suddenly changes the exact URL or the XML feed that the app needs, I can update that Web page and ensure that all installations of the app are using the correct XML feed. Does anyone have any advice or examples showing this kind of approach? It seems as if this must be a common problem, but so far I haven't found a well-established design pattern that fits it.

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  • how to handle exceptions/errors in php?

    - by fayer
    when using 3rd part libraries they tend to throw exceptions to the browser and hence kill the script. eg. if im using doctrine and insert a duplicate record to the database it will throw an exception. i wonder, what is best practice for handling these exceptions. should i always do a try...catch? but doesn't that mean that i will have try...catch all over the script and for every single function/class i use? Or is it just for debugging? i don't quite get the picture. Cause if a record already exists in a database, i want to tell the user "Record already exists". And if i code a library or a function, should i always use "throw new Expcetion($message, $code)" when i want to create an error? Please shed a light on how one should create/handle exceptions/errors. Thanks

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  • Is it okay if my ViewModel 'creates' bindable user controls for my View?

    - by j0rd4n
    I have an entry-point View with a tab control. Each tab is going to have a user control embedded within it. Each embedded view inherits from the same base class and will need to be updated as a key field on the entry-point view is updated. I'm thinking the easiest way to design this page is to have the entry-point ViewModel create and expose a collection of the tabbed views so the entry-point View can just bind to the user control elements using a DataTemplate on the tab control. Is it okay for a ViewModel to instantiate and provide UI elements for its View?

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  • Editing/Modifying a .java file programmatically? (not the .class file)

    - by Jay
    So, here is a piece of code using CodeModel that generates java code: JCodeModel cm = new JCodeModel(); JDefinedClass dc = cm._class("foo.Bar"); JMethod m = dc.method(0, int.class, "foo"); m.body()._return(JExpr.lit(5)); File f = new File("C:/target/classes"); f.mkdirs(); cm.build(f); This code generates a .java file: package foo; public class Bar { int foo() { return 5; } } However, I DO NOT want CodeModel to create a new java file for me. I do have a .java file already and would like to add a few lines of code to a method inside it. So, I would like the API to modify the java file directly/ create a modified copy of it. Is there a way to doing this?

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  • writing boot sector code

    - by JGC
    hi I want to write a code which put something in bootsector but when I run the assembly 8086 code which does this purpose, nothing happens. does any one know what can I do or does any one has code (in any language) which answer my need?

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  • algorithmes with no executable example code

    - by gcc
    [link] http://stackoverflow.com/questions/2932016/parsing-of-mathematical-expressions (problem has been told before) ** program is to create the infix tree for the given math expression.** if the expression is given completely paranthesized then the out put is fine but when there are no paranthesis or some part paranthesized then the out put is wrong. cant get the idea how to solve. my problem is told above. I have some algorithm to solve my problem, but I have no simple code which will be guide for me. Can anyone give me simple code (not working code) so that I will try working to understand.(for a 3 hours ,I have been searching and reading some text to understand algorithm which is told above.Actually,there is no example code investigating how it is working. Can anyone send me example which is written in c not other language.

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  • Are there any context-sensitive code search tools?

    - by Vicky
    I have been getting very frustrated recently in dealing with a massive bulk of legacy code which I am trying to get familiar with. Say I try to search for a particular function call, I get loads of results that turn out to be completely irrelevant; some of them are easy to spot, eg a comment saying // Fixed functionality in foo() so don't need to handle this here any more But others are much harder to spot manually, because they turn out to be calls from other functions in modules that are only compiled in certain cases, or are part of a much larger block of code that is #if 0'd out in its entirety. What I'd like would be a search tool that would allow me to search for a term and give me the choice to include or exclude commented out or #if 0'd out code. Then the search results would be displayed alongside a list of #defines that are required in order for that snippet of code to be relevant. I'm working in C / C++, but other than the specific comment syntax I guess the techniques should be more generally applicable. Does such a tool exist?

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  • Is foreign key reference from two different primary key from two different tables valid?

    - by arundex
    I have a foreign key that has to refer primary keys of two different tables. Table 1: animal animal_ id (primary key) Table 2: bird bird_ id (primary key) Table 3: Pet_info pet_id, type ENUM ('bird', 'animal') foreign key (pet_ id) references animal(animal_id), bird(bird_id) So, I need to check for pet_id either from animal or bird table depending on the need. Is this valid? Or should I go for some restructuring . . . NOTE: I referred this . . but I'm not sure whether I have to change my existing design

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  • Programmatically parse and edit C++ Source Files

    - by Kryten
    Hi, I want to able programmatically parse and edit C++ source files. I need to be able to change/add code in certain sections of code (i.e. in functions, class blocks, etc). I would also (preferably) be able to get comments as well. Part of what I want to do can be explained by the following piece of code: CPlusPlusSourceParser cp = new CPlusPlusSourceParser(“x.cpp”); // Create C++ Source Parser Object CPlusPlusSourceFunction[] funcs = cp.getFunctions(); // Get all the functions for (int i = 0; i &lt funcs.length; i++) { // Loop through all functions funcs[i].append(/* … code I want to append …*/); // Append some code to function } cp.save(); // Save new source cp.close(); // Close file How can I do that? I’d like to be able to do this preferably in Java, C++, Perl, Python or C#. However, I am open to other language API’s.

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  • C# DDD Populate Immutable Objects

    - by Russel
    Hi I have a immutable Customer class in my domain assembly. It contains the following GET properties : id, firstname and lastname. I have a CustomerRepository class in my persistence assembly. In turn, this CustomerRepository class should populate and return a Customer object using a remote web-serivce. My Customer class contains no setter properties and it contains a private constructor. The reason - I dont want the UI developer to get the wrong idea - He should not be able to create or change a Customer object. My question: How do I get my CustomerRepository to populate my Customer object. Reflection? Or should I sacrifice my design and enable a public constructor for constructing the customer object?

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  • Eclipse > Javascript > Code highlighting not working with Object Notation

    - by Redsandro
    I am using Eclipse Helios with PDT, and when I am editing JavaScript files with the default JavaScript Editor (JSDT), code highlighting (Mark Occurrences) is not working for half of the code, for example JSON-style (or Object Literal if you will) declarations. Little example: Foo = {}; Foo.Bar = Foo.Bar || {}; Foo.Bar = { bar: function(str) { alert(str) }, baz: function(str) { this.bar(str); // This bar *is* highlighted though } }; Foo.Bar.baz('text'); No Bar, bar or baz is highlighted. For now, I humbly edit the JavaScript part of projects in Notepad++ because it just highlights every occurrence of whatever is currently selected. Is there a common practice for Eclipse JavaScript developers to get code highlighting work correctly, using the popular Object Literal notation? An option or update I missed? -update- I have found that code highlighting depends on the code being properly outlined. Altough commonly used, Object Literal outlining still seems rare in javascript editors. the Spket Javascript Editor does partial Object Literal outlining, and the Aptana Javascript Editor does full Object Literal outlining. But both loses other important functionality. A quest for the editor with the least loss of functionality is currently in progress in this question.

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  • Stuck with the math in a Flash project, would parsing engine help?

    - by VideoDnd
    I've been stuck with the math in a Flash project? It's a loose design pattern my director formulated. My goal is to keep the project object oriented, and get 'non Flash obstacles' off my plate. Do you recommend using parsing engines for processing math? XML values going to AS3, updating a changing acceleration formula. I don't hate math, but it just doesn't seem OOP or good project planning to have the math stuck in Flash. Your comments are welcome.

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  • Location of code when sending HTML Email

    - by ChrisWesAllen
    I'm trying to figure out where to put some code in an email. You know how you can get newsletters with styling and images, etc? I wanted to send some out but I cant figure out where to put the code. Do you add the images as attachments? Do you put the code in the body? or should you upload the .html file as well?

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  • Transfer of directory structure over network

    - by singh
    I am designing a remote CD/DVD burner to address hardware constraints on my machine. My design works like this: (analogous to a network printer) Unix-based machine (acts as server) hosts a burner. Windows-based machine acts as client. Client prepares data to burn and transfers it to the server. Server burns the data on CD/DVD. My question is: what is the best protocol to transfer data over the network (Keeping the same directory hierarchy) between different operating systems?

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  • Stored Procedure or calculations via IQueryable?

    - by Shawn Mclean
    This is a question that is based on choosing performance over design practices. If I have a method that will be executed many times a second; public static IQueryable<IPerson> InRadius(this IQueryable<IPerson> query, Coordinate center, double radius) { return (from u in query where CallHeavyMathFormula(u, center, radius) select u); } This extension method for IQueryable generates a SQL that does some heavy maths calculation (Cosine, Sine, etc). This would mean the application sends 1-2KB of sql to the server per call. I've heard of placing all application logic, in your application. I also would like to change to a database such as azure or one of those scalable databases in the future. How do I handle something like this? Should I leave it as it is now or write stored procedures? How do applications like twitter or facebook do it?

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  • Should I dive into ASP.NET MVC or start with ASP.NET Webforms?

    - by Sahat
    I plan to pick up Silverlight in the future. Possibility of going into Microsoft WPF. Currently learning Objective-C 2.0 w/ Cocoa. I already know Pros and Cons of ASP.NET MVC vs ASP.NET Webforms. What I want to know is what would be more "efficient" for me to learn given the circumstances above? By efficient I mean learning one design pattern once and then re-using it. Objective-C I believe uses MVC approach? What about Silverlight? WPF? So what do you think? Also as a side question is it true that ASP.NET Webforms is often used by freelancers/small companies and ASP.NET MVC in large enterprises?

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  • High quality software examples

    - by Francisco Garcia
    One of the best ways to learn about programming is reading high quality code/projects from great engineers. Which open-source projects do you think is worth looking at? I mean, that code that you can print and sit under a tree with a glass of wine and enjoy reading. If you can, also specify if the software is great to look at because its documentation, design, UML diagrams or just plain code. I believe UML is not very common within open-source projects. Is there such a thing as a project branch that polishes code and design with the sole objective to give other programmers a great example of great software?

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  • Session State Anti-Pattern

    - by Curiosity
    I know the SOLID principles and other design patterns fairly well and have been programming for some time now - seeing many a bit of code throughout the years. Having said that, I'm having trouble coming up with a name to give the pattern, or lack thereof, to bits of code I've been dealing with at a current engagement. The application is an ASP.NET C# WebForms application, backed by a SQL Server/Mainframe backend (more mainframe than backend) and it's riddled with Session State properties being accessed/mutated from multiple pages/classes. Accessing/mutating global variables/application state was usually shunned upon while I was in school. Apparently the creators of this magnificent application didn't think it was such a bad idea. Question: Is there a name for such a pattern/anti-pattern that relies so heavily on Session State? I'd like to call the pig by its name ...

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